TH 7720 

C2 —_ — - -- 

Copy 1 

Tentative 
General Lighting 
Safety Orders 

1 . 

Issued by the 

Industrial Accident Commission 

of the 

State of California 


525 MARKET STREET, SAN FRANCISCO 
UNION LEAGUE BUILDING, LOS ANGELES 


Public Hearings on these Tentative Safety Orders 
will be held as follows, beginning at 10 a.m.: On 
June 5, 1919, in Room 307, 525 Market Street, San 
Francisco; on June 12, 1919, in Room 405, Union 
League Building, Los Angeles. 



CALIFORNIA STATE PRINTING OFFICE 
SACRAMENTO 
19 19 


44109 

















TWirz° 

.C'a 


INDUSTRIAL ACCIDENT COMMISSION 
OF THE STATE OF CALIFORNIA 


525 Market Street, San Francisco 

423 Union League Building, Los Angeles 

A. J. PILLSBURY, Chairman. 

WILL J. FRENCH. 

MEYER LISSNER, 


Commissioners. 


JOHN R. BROWNELL, 

Superintendent of Safety. 


m 27 1913 


9. of u. 






SUMMARY OF THE SAFETY PROVISIONS 


of the 

Workmen’s Compensation, Insurance and Safety Act. 

Being Chapter 176 of the Laws of 1913 as Amended by Chapter 607 of the 
Laws of 1915, and Chapter 586 of the Laws of 1917. 

Sections 33 to 54, inclusive, of the Workmen’s Compensation, Insur¬ 
ance and Safety Act give the Industrial Accident Commission power to 
make and enforce safety orders, rules and regulations, to prescribe safety 
devices, and to fix safety standards. It also empowers the Commission 
to. appoint advisers who shall, without compensation, assist the Com¬ 
mission in establishing standards of safety. The Commission may adopt 
and incorporate in its general orders such safety recommendations as it 
may receive from such advisers. 

The Commission, carrying out its plan of obtaining the 
best practical ideas to incorporate in its Safety Orders, asked 
various interests to serve on a committee to draft Tentative 
General Lighting Safety Orders. 

Committee on Tentative General Lighting Safety Orders. 
Romaine W. Myers (chairman), illuminating engineer, representing the 
National Council of Defense, Divisional Committee on Lighting. 

L. E. Voyer (vice chairman), illuminating engineer, General Electric 
Company, representing the Association of Electrical Manufacturers 
and the Lighting Fixture Association. 

W. W. Hanscom, electrical and mechanical engineer, representing the 
National Electric Light Association, Pacific Coast Section. 

Smith O’Brien, architect, representing the American Institute of 
Architects. 

R. H. Fenkhausen, electrical engineer, Bethlehem Shipbuilding Corpo¬ 
ration, Union Plant, representing the American Institute of Electrical 
Engineers. 

Daniel C. Murphy, president California State Federation of Labor. 

Paul Scharrenberg, secretary-treasurer California State Federation 
of Labor. 

R. S. Prussia, illuminating engineer, Westinghouse Lamp Company, 
representing the Association of Electrical Manufacturers. 

Miles F. Steel, Benjamin Electric Manufacturing Company, repre¬ 
senting the Association of Electrical Manufacturers. 

S. J. Lisberger, engineer of electrical distribution, Pacific Gas and 

Electric Company, representing the Pacific Coast Gas Association. 
Chas. M. Masson, illuminating engineer, Southern California Edison 
Company, representing the illuminating Engineering Society. 
Constant Meese, Meese & Gottfried Company, representing the San 
Francisco Chamber of Commerce. 

F. Dohrmann, Jr.,' Nathan-Dolirmann Company, representing the San 
Francisco Chamber of Commerce. 

Harry Gorman, field agent, representing the Bureau of Labor Statistics. 
IT. B. Woodill, president Woodill & Hulse Electric Company, Inc., 
representing the Merchants and Manufacturers Association of Los 
Angeles. 

W. A. Chowen, manager California Inspection Rating Bureau, repre¬ 
senting the Casualty Underwriters Board of California. 

D. Ayre, superintendent inspection department, California Inspection 
Rating Bureau, representing the Casualty Underwriters Board of 
California. 

Harold Mestre, representing the Industrial Welfare Commission. 

R. L. Eltringham, electrical engineer, representing the Industrial 
Accident Commission. 

John R. Brownell (secretary), superintendent of safety, Industrial 
Accident Commission. 


Acknowledgment is made of the assistance rendered by the Illuminating 
Engineering Society in the preparation of these Tentative Orders, and for 
the use of the various cuts which they kindly loaned. 



4 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 
Order 1500. Definitions. 

(а) Candle (or candlepower) means the unit of luminous 
intensity maintained by the national laboratories of the United 
States, France and Great Britain. 

(б) Lumen means the unit of luminous flux, and is the 
quantity of light necessary to produce an average intensity of 
illumination of one foot-candle over an area of one square foot. 

(c) Foot-candle means the unit of illumination equal to one 
lumen per square foot. It is the lighting effect produced upon 
an object by a lamp of one candlepower at a distance of one 
foot. 

(d) Photometer means a standardized instrument suitable 
for making illumination measurements. 

(e) Lamp means that part of the lighting equipment from 
which the light originates. 

(/) Local lamps (or lighting) means lighting units located 
close to the work, and intended to illuminate only a limited 
area about the work. 

(g) Overhead lamps (or lighting) means lighting units 
installed above ordinary head-level to secure a general illumi¬ 
nation over a considerable area. 

(h) Brightness means the intensity of light per unit area 
emitted from, or reflected by, a body; and in these Orders 
is expressed in candlepower per square inch. 

(i) Glare means any brightness within the field of vision of 
such a character as to cause discomfort, annoyance, interfer¬ 
ence with vision, or eye fatigue. 

(j) Eyestrain means a physiological condition of the eye 
resulting in discomfort, poor vision, or fatigue. 

(k) Shaded means that the lamp is equipped with'a reflector, 
shade, enclosing globe, or other accessory for reducing the 
brightness in certain directions, or otherwise altering or chang¬ 
ing the distribution of light from the lamp. 

( l ) Illumination means the quantity of light thrown upon 
an object by a luminous body; it is measured in foot-candles 
per square foot of area. 

(m) Intensity of illumination means the foot-candles per 
square foot of area. 

(n) Foot-candles at the work means the intensity of illumi¬ 
nation on the object upon which work is being performed. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 5 

(o) Foot-candles at floor-level means the intensity of illumi¬ 
nation on the floor of the space specified. 

Order 1501. General Requirements. 

(a) Working or traversed spaces in buildings or grounds 
of places of employment shall be supplied during the time of 
use, with either natural or artificial light in accordance with 
the following Orders (1502-1509). 

Order 1502. Natural Lighting. 

(a) Windows, skylights or other roof-lighting construction 
of buildings shall be arranged with the glass area so appor¬ 
tioned that at the darkest part of any working space, when 
normal exterior daylight conditions obtain (sky brightness of 
1.50 candlepower per square inch) there will be available a 
minimum intensity equal to twice that of Order 1503, other¬ 
wise artificial light of intensities specified in Order 1503 shall 
be provided. 

( b ) Awnings, shades, diffusive or refractive window glass 
shall be used for the purpose of improving daylight conditions 
or for the avoidance of eyestrain wherever the location of the 
work is such that the worker must face large window areas 
through which excessively bright light may at times enter the 
building. 

Note.— The intensity requirements for adequate day lighting are much 
higher than those for adequate night lighting, because in general under 
daylight conditions the light reaching the eye from all surroundings in the 
field of vision is much brighter than at night, and hence a correspondingly 
more intense light must fall on the object viewed. 

Order 1503. Artificial Light. 

(a) When the natural light is less, than twice the minimum 
permissible intensities of illumination set forth in the following 
table, artificial light shall be supplied and maintained in 
accordance with the tabla 

Note. —See Appendix for intensities recommended for best working 
conditions. 

Foot-candles at the floor level 


1. Roadways and yard thoroughfares_ 0.02 

2. Storage spaces, stairs, stairways, halls, hallways, 

passageways, aisles, exits and elevator en¬ 
trances _ 0.25 

3. Water-closet compartments, toilet rooms, wash¬ 

rooms, dressing rooms and elevator cars- 0.50 


2—44109 





6 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


Foot-candles at the work 

4. Work not requiring discrimination of detail, such 

as handling material of a coarse nature, and 
performing operations not requiring close 
visual application_ 0.50 

5. Rough manufacturing requiring discrimination of 

detail, such as rough machining, rough assem¬ 
bling, rough bench work, also work in base¬ 
ments of mercantile establishments requiring 
discrimination of detail_ 1.00 

6. Rough manufacturing requiring closer discrim¬ 

ination of detail, such as machining, assembly 
and bench work, also work in basements of 
mercantile establishments requiring closer dis¬ 
crimination of detail, intermediate between 


5 and 7_ 2.00 

7. Fine manufacturing, such as fine lathe work, pat¬ 

tern and tool making, also office work, such as 
accounting and typewriting_ 3.00 

8. Special cases of fine work, such as watchmaking, 

engraving and drafting_ 5.00 

9. Processes otherwise safeguarded in which light is 

detrimental _+_ 0.00 


Note.— Some exceptions to the intensity rule: 

(а) There are some operations that are performed in compar¬ 
ative darkness, as for example, photographic processes in the 
dark room. 

(б) There are some operations that are best observed by their 
own light, as in parts of the process of working glass. 

(c) Some operations are best observed by the “silhouette” 
method of lighting in which the work is seen against a lighted 
background in a comparatively dark room, as in some processes of 
working with dark threads and lamp filaments. 

In all such cases in which work is of necessity carried on in 
comparative darkness, special precautions should be taken to 
properly safeguard the workmen. 

Order 1504. Measurements. 

(a) For the purpose of light measurements, a standardized 
photometer, certified by the Industrial Accident Commission of 
the State of California, shall be used, and such measurements 
shall be made at the locations specified in the table. 

Order 1505. Shading of Lamps for Overhead Lighting. 

(a) Lamps suspended at elevations above eye level less than 
one-quarter their distance from any positions at which work 
is performed, must be shaded in such a manner that the 








TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


7 


intensity of the brightest square inch of visible light source 
shall not exceed seventy-five candlepower. 

Note. — The following diagram illustrates the application of the above 
rule, the distances being explanatory and representing the ratio between 
the height of the lamp above the eye level and its horizontal distance 
from the eye. 


x~ 


CEILING LINE-* 




Lamps below the Limit here shown 
must be so shaded that the Candie- 
power of the brightest 5g in. of the 
Light Source shall not exceed 75 



Most distant 
Lamp from any 
FOintat which 


Work is per¬ 
formed 




mr 

•A Limited Height or K 
: of Mountinq ; 

.y, _ 




<-END OF ROOM 


END OF ROOM 


FLOOR LEVEL 




Exception . Lamps suspended at elevations greater than 
twenty feet above the floor are not subject to this requirement. 

Note 1.—Glare from lamps or unduly bright surfaces produces eye- 
strain and increases the accident hazard. The brightness limit specified 
in this Order is an absolute maximum. Very much lower brightness 
limits are necessary in many interiors illuminated by overhead lamps, if 
the illumination is to be satisfactory. In some cases the maximum 
brightness should not exceed that of the sky (two to three candlepower 
per square inch). 

Note 2.—Where the principal work is done on polished surfaces, such 
as polished metal, celluloid, varnished wood, etc., it is desirable to limit 
the brightness of the lamps in all downward directions to the amount 
specified in this Order. 

Note 3.—For method of measuring brightness, see Appendix, para¬ 
graph 86. 


Order 1506. Shading of Lamps for Local Lighting. 

(a) Lamps for local lighting must be shaded in such a 
manner that the intensity of the brightest square inch pre¬ 
sented to view from any position at which work is performed, 
shall not exceed three candlepower. 

Note. —In the case of lamps used for local lighting, at or near eye 
level, the limits of permissible brightness are much lower than for lamps 
used for overhead lighting, because the eyes are more sensitive to strong 
light received from below, and because such light sources are more 
constantly in the field of view. 













8 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

Order 1507. Distribution of Light on the Work. 

(a) The reflectors or other accessories, mounting heights and 
spacings employed with lamps shall be such as to secure a 
reasonably uniform distribution of illumination, avoiding 
objectionable shadows and sharp contrasts of brightness. If 
local lighting is used, there shall be employed in addition a 
moderate intensity of overhead lighting, with a minimum of 
not less than one-fourth (£) foot-candle. 

Exception. Where the light from the local lamps falls 
principally upon surfaces which are white or nearly so, and 
the ceilings and walls of the rooms are light, there is often a 
sufficient general illumination received indirectly by reflection 
to obviate the necessity of additional overhead lighting. 

Note.—W hen local lighting is used as the sole source of illumination 
of an interior, the field of illumination from each lamp is in contrast to 
the surrounding darkness, thereby causing eyestrain and increasing the 
accident haza-rd. 

Order 1508. Emergency Lighting. 

(a) Emergency lights shall be provided in all workspace 
aisles, stairways and passageways; at all exits, and on all out¬ 
side landings of fire-escapes or other structures used as regular 
or emergency means of egress to provide for reliable operation 
when, through accident or other cause, the regular lighting is 
extinguished. 

Note 1. —It is the intention of this Order to guard against accident 
due to the failure of the regular lighting system, by providing sufficient 
illumination to enable the occupants to: 

(a) Avoid contact with moving machinery and other danger points 
until the regular lighting is again placed in operation. 

(&) To vacate the building safely and expeditiously when this is 
necessary because of fire or other causes. 

Note 2. —Emergency lighting may be installed in various ways. The 
method to be employed depends upon the size of the premises, the extent 
of the hazards of employment, and the means available for supplying 
such emergency lighting. 

(5) Emergency lighting systems, including all supply and 
branch lines, shall be entirely independent of the regular 
lighting system and shall be lighted concurrently with the 
regular lighting system and remain lighted throughout the 
period of the day during which artificial light is required or 
used. 

(c) Emergency lighting, where required, shall have a mini¬ 
mum intensity of one-fourth (£) foot-candle. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 9 

(d) Emergency lighting systems shall, where the nature 
of the hazard is such as to require it, be supplied from a source 
independent of the regular lighting system wherever possible. 
This source of supply and controlling equipment shall be such 
as to insure the reliable operation of the emergency lighting 
system when, through accident or other cause, the regular 
lighting system is extinguished. Where a separate source of 
supply can not be obtained for the emergency lighting the feed 
for emergency lights must be taken from a point on the street 
side of the service equipment. Where source of supply for 
the regular lighting system is an isolated plant within the 
premises, an auxiliary lighting system of sufficient capacity to 
supply all emergency lighting must be installed from some 
other source, or suitable storage battery; or separate gener¬ 
ating unit may he considered the equivalent of such service. 

Order 1509. Switching and Control Apparatus. 

( a ) Switches or other controlling apparatus shall be so 
installed that pilot or night lights may be controlled from a 
point at the main entrance, and other easily accessible points. 
Pilot or night lights may he a part of the emergency lighting 
system. 

(5) All switching and control apparatus on emergency, 
pilot and night lights shall be plainly labeled for identification. 

Note.—T he purpose of this Order is to make it possible for the night 
watchman or other qualified persons to turn on enough lamps, when 
entering any portion of the premises at night, to enable them to safely 
see their way around without the need of a lantern or flashlight. 


10 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


APPENDIX. 

GENERAL INFORMATION AND SUGGESTIONS. 

1. The foregoing Orders give in the briefest possible form 
the essentials of proper and adequate lighting for factories, 
mills and other work places, general information with detailed 
discussion of the methods of applying the Orders being pre¬ 
sented in this Appendix. 

2. When adequate and satisfactory illumination is substi¬ 
tuted for the all too prevalent poor illumination in factories, 
mills and other work places, the results obtained are mutually 
beneficial to the employees, the employers, and the country as 
a whole. Under proper illumination conditions, the health, 
contentedness, safety and skill of the employees are maintained 
at a high standard, the output is increased in quantity and 
improved in quality, while there is a proportional reduction in 
the cost of each unit of finished products when it reaches the 
public. 

3. While it is desirable to have adequate light over the 
working areas, it is absolutely essential for the proper results 
to eliminate or minimize the light which otherwise would pass 
directly from the lamps to the eyes of the workers; that is, one 
must avoid glare which is not only fatiguing to the eye but 
also conducive to the incorrect estimation of sizes and locations 
of objects in the field of view. 

4. Glare effects may be caused not only by the light reaching 
the eye directly from the sources having a brightness greatly 
in excess of that of the objects viewed, but they may be pro¬ 
duced by excessive reflection from the objects within view. In 
factory lighting each lamp should be so located that the eye 
does not see it in the ordinary course of work, and so shaded 
or covered that brilliant reflections are avoided. The desired 
result can be obtained by putting over the lamp an open shade 
which screens it and reflects downward much of the light which 
would otherwise be of either no value or actually detrimental. 
Another way of accomplishing the same result is to surround 
the lamp with a diffusing globe dense enough not to reveal the 
form of the actual light source within, but to give the effect of 
the light pouring from the globe as a whole. Specific sugges¬ 
tions for various locations are contained in this Appendix. 

5. In the following descriptive matter may be found the 
elements of good illumination versed in such manner that it 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


11 


can be understood readily by the nontechnical mind. A 
perusal of this subject will convince one that, aside from the 
humanitarian standpoint, the expense incurred in obtaining 
satisfactory lighting will, in practically all cases, result in good 
financial returns. 

6. Minimum and desirable illumination. The minimum 
foot-candles in Order 1503 specify the lowest illumination with 
which the employee can be properly safeguarded against acci¬ 
dent. It is to the advantage of the employer to provide the cor¬ 
responding intensities of modern practice listed in the follow¬ 
ing table of desirable illumination, as such provision results in 
reduced eyestrain, greater accuracy of workmanship, increased 
production and less spoilage. 


Desirable Illumination. 


1. Roadways and yard thor¬ 

oughfares _ 

2. Storage spaces - 

3. Stairs, stairways, halls, hall¬ 

ways, passageways, aisles, 
exits, elevator entrances 
and elevator cars_ 

4. Work not requiring discrim¬ 

ination of detail_ 

5. Rough manufacturing re¬ 

quiring discrimination of 
detail_ 

6. Rough manufacturing re¬ 

quiring closer discrimina¬ 
tion of detail_ 

7. Fine manufacturing, ac¬ 

counting, typewriting- 

8. Special cases of fine work— 


Foot-candles 

at floor level Corresponding 
■—modern minimum— 

practice Order 1503 


0.05 

to 

0.25 

0.02 

0.50 

to 

1.00 

0.25 

1.00 

to 

2.00 

0.25-0.50 

1.00 

to 

2.00 

0.50 

2.00 

to 

4.00 

1.00 

3.00 

to 

6.00 

2.00 

4.00 

to 

8.00 

3.00 

7.00 

to 15.00 

5.00 


7. Table of Recommended Intensities for Detailed Operations and 
Processes. (Expressed in foot-candles.) 

Classification. 

Assembling . 

Rough assembling — 

Medium assembling _ 

Fine assembling- 

Extra fine assembling 


2- 4 

3- 6 

4- 8 
7-15 












12 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


Classification. 

Automobile manufacturing. 

(See machine shops, paint shops, woodworking 
shops, etc.) 

Bakeries. 

Mixing and baking _ 3-6 

Banks. 

Clerical and private offices _ 4-8 

Desk and cage lighting _ 4-8 

General illumination _ 1-2 

Barber shops _ 4—8 

Boiler, engine rooms and power houses. 

Boiler rooms _; r _ 2-4 

Coal and ash handling _'_ 2-4 

Engine rooms _ 3-6 

Auxiliary equipment _ 2-4 

Oil switch and transformer rooms _ 3-6 

Switchboards _ 3-6 

Storage battery rooms _ 2-4 

Brewing, distilling and bottling. 

Beer boiling _ 2-4 

Bottling _ 3-6 

Clearing or resting and fermenting _ 1-2 

Cool ship _ 1-2 

Keg washing _ 3-6 

Keg filling _ 3-6 

Button manufacturing. 

Grading machines, wet and dry polishing _ 1-2 

Grinding machines, cutting blanks and shells, card¬ 
ing buttons, hand turning, automatic machines _ 2-4 

Sorting of waste, sorting for thickness _ 3-6 

Grading for color and defects _,_ 7-15 

Candy making. 

Cooking over furnaces _ 3-6 

Cooling slabs _ 3-6 

Cream beater machines _ 3-6 

Dipping (hand) _ 3-6 

Dipping (machine) _ 3-6 

Moulding _ 3-6 

Revolving pan _ 3-6 

Spinning bench ___ 3-6 

Weights and measures _ 3-6 

Wrapping and packing _ 3-6 

Canning and preserving. 

Cooking _ 3-6 

Assorting, cleaning, cutting and peeling_ 3-6 

Hand filling _ 3-6 

Machine filling _ 3-6 





































Tentative general lighting safety Orders. 13 

Classification. 

Chemical works. 

Furnaces__ 2-4 

Tanks or cooking, extractors, percolators, nitrators_ 3-6 

Generators and stills_ 3_6 

Drying_____ 2-4 

Evaporators _ 3_6 

Filtration _ 3 _g 

Grinding _■_ 3_g 

Crystallizing ___ 3_6 

Bleaching _ 3 _g 

Electrolytic cells__ 3-6 

Clay products and cements. 

Enameling_ 3_6 

Grinding ___ 2-4 

Filter press rooms__ 2-4 

Moulding and pressing_ 3-6 

Cleaning and trimming_ 3-6 

Coloring and glazing___ 4-8 

Kiln rooms ___ 2-4 

Cloth products. ^ 

Cutting - 4-8 7-15 

Sewing (machine) _ 4-8 7-15 

Sewing (hand) _ 4-8 7-15 

Pressing_;_ 4-8 7-15 

Inspecting _ 4-8 7-15 

Cloth treating (oilcloth, etc.)__ 4-8 7-15 

Dairy products. 

Separators, evaporators, churns, moulds and presses 3-6 

Pasteurizing _ 3-6 

Bottling, canning and labeling_ 3-6 

Ice cream freezers____ 3-6 

Depots. 

Baggage rooms_ 1-2 

Dining rooms _ 3-6 

General offices- 4-8 

Waiting rooms- 2-4 

Loading platforms_ 1-2 

Draughting rooms _ 7-15 

Electric manufacturing. 

Coil and armature winding- 4-8 

Mica working- 4-8 

Insulation moulding--- 4-8 

Other insulating processes-'-- 4-8 

Storage battery moulding- 3-6 

Lamp manufacturing- ? - ? --- 7-45 

Wire insulating- 4-8 

3—44109 








































14 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


Classification. 

Fertilizer manufacturing. 

Cookers, pressers, fertilizer dryers, fertilizer mills- 
Forge shops and welding. 

Rough forging _ 

Fine forging _*_ 

Drop forging __ 

Foundries. 

Rough moulding _ 

Fine moulding __ 

Core making _;__ 

Charging floor _ 

Tumbling and cleaning _ 

Glass vjorks. 

Mix room ___ 

Furnace room _ 

Casting and lehr _ 

Grinding _ 

Fine grinding and polishing _ 

Glass-blowing machines _ 

Cutting glass to size _ 

Glass cutting (cut glass) _ 

Beveling__ _ 

Silvering _ 

Inspecting _ _ ___ 

Etching and decorating _ 


Glove manufacturing. 

Sorting _ 4-8 

Cutting _ 3-6 

Stitching _ F-8 

Trimming and inspecting _ 4-8 

Pressing _ 3-6 

Knitting _*_ _ ___ 3-6 


Grinding, Buffing and polishing. 

Rough work _ 

Medium work _ 

Fine work ___ 


2-4 


2- 4 

3- 6 
3-6 


2- 4 

3- 6 
3-6 
2-4 
2-4 


2-4 

2-4 

2- 4 

3- 6 

4- 8 

2- 4 

3- 6 
7-15 

4- 8 

3- 6 
7-15 

4- 8 

Dark 

goods. 

7-15 

4-8 

7-15 

7-15 

4-8 

4-8 


2- 4 

3- 6 

4- 8 


Halls, stairways, passageways and aisles _ 

Hat manufacturing. 

Forming, sizing, pouncing, flanging, finish¬ 


ing and ironing_ 3-6 

Dyeing and stiffening_ 2-4 

Braiding_,_ 2-4 

Cleaning and refining_ 2-4 

Sewing _ 4-8 


1-2 

Dark 

goods. 

4-8 

3-6 

3-6 

3-6 

7-15 





































TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


15 


Classification. 

Hospitals. 

Corridors _ 

Wards, general (supplemented by local) _ 

Wards, with no local lighting _ 

Laboratories ___ 

Operating tables _ 

(See boiler and engine rooms, laundries, kitchens, 
dining rooms, storage spaces, etc.) 

Hotels. 

Kitchens ___ 

Dining rooms _ 

(See engine and boiler rooms, offices, storage spaces, 
stairways, passageways, laundries, etc.) 

Ice making _ 

Inspecting. 

Rough inspecting _ 

Medium inspecting _•_ 

Fine inspecting _ 

Extra fine inspecting _'___ 

Jewelry and watch manufacturing. 

Bench work and extra fine machine work _ 

Machine work _^__ 

Stamping ___ 

Engraving _ 

Jewel working _ 

Laundries and dry cleaning. 

Sorting and marking _ 

Washing _ _ _ 

Mangles and machine ironing -- 

Pressing and hand ironing _ 

Dry and steam cleaning. __-_ 

Leather manufacturing. 

Cleaning, tanning, stretching, etc _ 


Cutting, fleshing and stuffing- 

Finishing and scarfing- 

Leather working. 

Grading and matching- 4-8 

Cutting and scarfing- 4-8 

Sewing_ 4-8 

Pressing and winding_ 3-6 

Libraries _ 


(See other classifications relating to corresponding 
quarters.) 

Locker, toilet and wash rooms - 


0.5 

0.5 

1-3 

3-6 

25-40 


2- 4 

3- 6 


2-4 


2- 4 

3- 6 

4- 8 
7-15 


7-15 

7-15 

7-15 

7-15 

7-15 


3-6 

2- 4 

3- 6 
3-6 
3-6 


2- 4 

3- 6 

4- 8 

Dark 

goods. 

7-15 

4-8 

7-15 

4-8 

3-6 


2-4 

































16 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


Classification. 

Machine shops. 

Rough bench and machine work_ 2-4 

Medium bench and machine work_ 3-6 

Fine bench and machine work_ 4-8 

Extra fine bench and machine work_ 7-15 

Automatic machines (ordinary)_ 3-6 

Automatic machines (fine)_____ 4-8 

Meat packing. 

Slaughtering _ 2-4 

Cleaning and cutting_ 3-6 

Cooking ___ 3-6 

Grinding and packing_ 3-6 

Canning_ 3-6 

Milling and grain food products. 

Cleaning__ 2-4 

Grinding or rolling___ 2-4 

Baking or roasting_ 3-6 

Offices __ 4-8 

Packing. 

Rough_ 3-6 

Fine _ 4-8 

Paint manufacturing _ : _ 2-4 

Paint shops. 

Dipping or spraying_ 3-6 

Rubbing ____ 3-6 

Firing _ 2-4 

Hand painting and finishing, ordinary_ 3-6 

Hand painting and finishing, fine_ 4-8 

Hand painting and finishing, extra fine (automobile 

bodies, piano cases, etc.)_ 7-15 

Paper box manufacturing. goo^s 1 goods 

Cutting_ 2-4' 3-6’ 

Machine folding__ 2-4 3-6 

Hand folding_ 2-4 3-6 

Pasting and assembling_ 2-4 3-6 

Paper manibfacturing. 

Beaters_ 2-4 

Calendering_,__ 3-6' 

Machine ____ 3-6 

Grinding _ 2-4 

Finishing, cutting and trimming_ 4-8 

Plating. 

Plating- 3-6 

Polishing and burnishing___ 3-6 





































TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


17 


Classification. 

Printing industries. 

Linotype and monotype _ 7-15 

Typesetting- 7-15 

Composing stone_ 7-15 

Matrixing and casting_ 3-6 

Miscellaneous machines_ 3-6 

Proofreading_ 4-8 

Presses, job and small automatic_ 3-6 

Presses, rotary, flat, bed, etc_ - 3-6 

Lithographing__ 4-8 

Electrotyping _ 4—8 

Engraving _ 7-15 

Receiving and shipping _ . _ 2-4 

Restaurants. (See Hotels.) 

Roadways and yard thoroughfares _0.05-0.25 

Rubber manufacturing and products. 

Calendering _ 3-6 

Grinding ____ 3-6 

Vulcanizing_ ; _ 3-6 

Washing and compounding rolls_ 3-6 

Sheet metal working. 

Bench work, ordinary__ 3-6 

Bench work, fine_ 4-8 

Punches, presses, shears, stamps and welders__ 4-8 

Spinning__ 4-8 

Miscellaneous machines_ 3-6 


Shipbuilding. 

(See machine shops, sheet metal working, roadways, 
yard thoroughfares, woodworking, assembling, 
etc.) 


Shoe manufacturing. 'good£. 

Inspecting and sorting raw material_ 4-8 

Cutting _ 3-6 

Stitching, machine_7-15 

Stitching, hand_ 4-8 

Lasting and welding_ 4-8 

Hand turning_ 3-6 

Miscellaneous bench and machine work_ 3-6 


Soap manufacturing. 

Kettle houses - 

Framing_ 

Cutting_ 

Stamping, wrapping and packing. 

Soap chip _ 

Soap powder__ 

Filling and packing soap powder. 


Dark 

goods. 

7-15 

4-8 

7-15 

7-15 

4-8 

3- 6 

4- 8 


2-4 

1-2 

2- 4 

3- 6 
2-4 

2- 4 

3- 6 





































18 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


Classification. 

Steel and iron mills, bar, sheet and wire products. 


Automatic machines--- 3-6 

Charging floor_ 2—4 

Casting floor- 2-4 

Soaking pits and reheating furnaces- 2-4 

Rolling mills- 3-6 

Shears, presses, punches and riveters- 3-6 

Rod mill _ 3-6 

Wire drawing, coarse_ 3-6 

Wire drawing, fine-- 4-8 

Pickling and cleaning- 2-4 

Stone cutting. 

Machine cutting_ 2-4 

Hand cutting_ 2-4 

Carving - 3-6 

Polishing _ 3-6 

Store and stock rooms. 

Rough stock_____ 2-4 

Medium stock_ 3-6 

Fine stock--- 4-8 

Stores. : S il 


(Satisfactory store lighting requires that considera¬ 
tion he given so many different factors, such as 
location, color of finish, size and shape, location 
and character of displays, as to make it impossible 
to compile a complete list. The following tabu¬ 
lation is general, only, and it is recommended that 
expert advice be obtained where any doubt exists 
as to the proper allowances to be made.) 


Automobile showrooms_ 2-6 

Art (light on exhibits)_ 5-10 

Book _•_ 3-5 

Baker _ 2-4 

Butcher_ 2-4 

China_^_ 2-3 

Cigar - 4-6 

Clothing_ 4-7 

Cloak and suit_ 4-7 

Candy_ 3-6 

Confectionery _ 3-5 

Decorator__ 4-5 

Department (see each department). 

Drug_ 2-4 

Dry goods__ 4-7 

Florist ___:_ 2-3 

Furniture ___ 2-4 

Furrier_ 5-8 




































TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 19 

Classification. 

Grocery _ : __ 2-4 

Haberdasher (men’s furnishings)_ 5-7 

Hardware _ 2-4 

Hat ___ 4-6 

Jewelry _;__4-6 

Millinery _ 4—6 

Music _:_ 2-4 

Notions_ 3-5 

Piano _ 2-4 

Rug racks_10-20 

Shoe _;_ 2-4 

Stationery_ 2-4 

Tailor _____ 4-6 

Tobacco (see cigar). 

Schools. 

Auditoriums :_ 2-4 

Blackboards____ 3-5 

Classrooms, study rooms, libraries, laboratories_ 3-6 

Gymnasiums ____ 3-6 

Sewing, drafting_1_ 7-15 

Shop work (rough)_ 2-4 

Shop work (fine)_:_ 4-8 

Stairways, corridors, toilets, hat and cloakrooms, etc. 1-2 

Storage spaces _0.5-1 

Telegraph. 

Operating ___ 4-8 

Telephone. 

Automatic exchanges_ 4-8 

Manual exchanges_ 3-6 

Testing. 

Rough __ 2-4 

Medium _ 3-6 

Fine _ 4-8 

Extra fine_ 7-15 

Textile mills. T • u* ^ , 

~ ,, Light Dark 

Cotton - goods. goods. 

Opening and lapping_ 2-4 2-4 

Carding _ 2-4 2-4 

Drawing frame- 2-4 2-4 

Roving, spooling, spinning, etc_ 3-6 3-6 

Warping _ 2-4 2-4 

Slashing---—- 2-4 2-4 

Drawing in--- 3-6 3-6 

Weaving _ 3-6 3-6 

Dyeing _ 3-6 3-6 






































20 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


Classification. 

Silk — 

Winding_ 3-6 3-6 

Throwing___ 3-6 3-6 

Quilling and warping_ 3-6 4-8 

Weaving___ 3-6 4-8 

Dyeing _ 3-6 3-6 

Finishing__ 3-6 4-8 

Woolen — 

Picking___ 3-6 3-6 

Washing and combing__ 3-6 3-6 

Carding _ 2-4 2-4 

Twisting_ 3-6 3-6 

Dyeing _ 3-6 3-6 

Drawing in___ 3-6 4-8 

Warping _ 3-6 4-8 

Weaving ______ 4-8 7-15 

Perching_ 7-15 7-15 

Knitting machines, ordinary and nappers_3-6 3-6 

Knitting machines, flat and others_ 4-8 4-8 

Cordage mills_ 3-6 3-6 

Tobacco products ___ 3-6 

Warehouses ___ 2-4 

(See other classifications.) 

Woodworking. 

Rough sawing (sawmills)_ 2-4 

Sizing, planing, rough sanding, etc_ 3-6 

Machine woodworking, medium_ 3-6 

Machine woodworking, fine_!_ 4-8 

Bench work, medium. __ 3-6 

Bench work, fine_,__ 4-8 

Fine sanding and finishing_ 4-8 

Gluing and veneering_ 3-6 

Cooperage _ 3-6 


DAYLIGHT. 

8. Importance of daylight. Adequate daylight facilities 
through large window areas, together with light, cheerful sur¬ 
roundings, are highly desirable and necessary features in 
every work place, and they should be supplied through the 
necessary channels not only from the humane standpoint, but 
also from the point of view of maximum plant efficiency. The 
unusual attention to gas and electric lighting in factories, 
mills and other work places during the past few years; the 
perfection of various lamps and auxiliaries by means of which 
an improved quality and quantity of lighting effects are 






























TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 21 

obtained; and the care which has been devoted to increasing the 
efficiency in various industrial operations—all go to emphasize 
the many advantages and economies that result from suitable 
and adequate window space as a means for daylight in the 
proper quantities and in the right directions during those por¬ 
tions of the day when it is available. 

9. Three considerations. Three important considerations of 
any lighting method are sufficiency, continuity and diffusion. 
With respect to the daylight illumination of interiors,~ suffi¬ 
ciency demands adequate window area; continuity requires 
(a) large enough window area for use on reasonably dark days, 
(&) means for reducing the illumination when excessive due to 
direct sunshine, and (c) supplementary lighting equipment for 
use on particularly dark days and especially toward the close 
of winter days; diffusion demands interior decorations that are 
as light in color as practicable for ceilings and upper portions 
of walls, and of a dull or mat finish in order that the light 
which enters the windows or that which is produced by lamps, 
may not be absorbed and lost on the first object that it strikes, 
but that it may be returned by reflection and thus be used over 
and over again. Diffusion also requires that the various sources 
of light, whether windows, skylights or lamps, be well distrib¬ 
uted about the space to be lighted. Light colored surroundings 
as here suggested result in marked economy, but their main 
object is perhaps not so much economy as to obtain a result 
that will be satisfactory to the human eye. 

10. Requirements. The following requirements may now be 
listed for natural lighting: 

1. The light should be adequate for each employee. 

2. The windows should be so spaced and located that daylight 
conditions are fairly uniform over the working area. 

3. The intensities of daylight should be such that artificial 
light will be required only during those portions of the day 
when it would naturally be considered necessary. 

4. The windows should provide a quality of daylight which 
will avoid a glare due to the sun’s rays and light from the sky 
shining directly into the eye, or where this does not prove to 
be the case at all parts of the day, window shades or other 
means should be available to make this end possible. 

5. Ceilings and upper portions of walls should be maintained 
a light color to increase the effectiveness of the lighting facil- 


4—44109 


22 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

ities from window areas. The lower portions of walls should 
be somewhat darker in tone to render the lighting restful to the 
eye. Factory green or other medium colors may be used to 
good effect. 

11. Classification. Means for natural lighting may be 
classed under three broad divisions as follows: 

(a) That case in which the windows are located on the sides 
of the building or in the framework of saw-tooth construction 
where diffused light from the sky reaches the work during a 
large portion of the day. 

fib) That case in which windows are located overhead on a 
horizontal or nearly horizontal plane in the form of skylights, 
thus furnishing direct light from the sky during a large portion 
of the day. 

(c) That case in which prismatic glass takes up the direct 
light from the sky and redirects it into the working space. 

Method (a) is, of course, the most common of the three, and 
it may be noted that the saw-tooth or other roof-lighting con¬ 
structions have become very popular and result in an excellent 
quality and quantity of light for given window areas, provided 
the size and location of windows are in accord with , modern 
practice. 

12. Increasing the value of floor space. Adequate and well 
distributed natural light means that certain portions of the 
floor space which ordinarily would not be available for work, 
are converted into valuable manufacturing space. In a gen¬ 
eral way, therefore, the average factory, mill or other work 
place, if properly designed, should possess natural lighting 
facilities which produce the best practicable distribution of 
daylight illumination. 

13. Wide aisles. With low ceilings and very wide aisles, 
workmen located at the central portion of the building must 
sometimes depend for their natural light on windows located 
at a considerable distance away from their working position. 
In these cases it may be possible, in general, to depend alto¬ 
gether on daylight over an entire floor space, even at those 
times of the day when daylight conditions would be entirely 
adequate under other circumstances. This statement applies 
to side windows rather than to skylights or to saw-tooth con¬ 
struction. Fig. 1 illustrates this feature. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


23 


14. Varying conditions. In a case of this kind, employees 
located next to the windows are furnished with suitable day¬ 
light in the early morning and towards the latter part of the 
afternoon, the upper portions of the windows being particu¬ 
larly serviceable in lighting areas at some distance away from 
the windows. A southern exposure, however, results in such 
excessive light from the sky during the middle of the day, that 
heavy shades are nearly always pulled down so as to cover the 


REGION OFCOM- 
PARITIVE ABSENCE 




these desks receive 


OFD/ff LIGHT:ARTI- ADEQUATE DAY LI / 

FILIAL DAYLIGHT / / 

Required nearly / , 

.ALLDAY _V ! / ->_ 


0 

0 

0 

0 

0 


0 0 0 

0 0 0 

0 0 0 

0 0 0 

- 50 ’- 

0 0 0 


plan 

F’ig. 1. Diagram of a large office 
with windows on one side 
only. 


entire window area. ‘This plan makes it necessary to use arti¬ 
ficial light throughout the larger part of the office during the 
brightest portion of the day, and reduces the daylight at those 
points where it would supposedly be the best, namely, near the 
windows. Here the location of the windows is a large factor 
in the excellence of the daylight conditions, but the manipula¬ 
tion of the shades is perhaps even more important. To avoid 
such difficulty, adjustable translucent upper window shades 
with adjustable opaque lower shades might be employed. 

15. Upper portions of windows. It should be further noted 
in this illustration that the upper portions of the windows give 
a reduced illumination in proportion to their areas, to the floor 
space near them: In rooms of moderate size, therefore, the 













24 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


windows should be placed as near the ceiling as practicable. 
When the sun shines through windows so located, the direct 
light must be reduced or diffused. This may be accomplished 
by the use of ribbed glass in ordinary factory and mill build¬ 
ings, and in offices by the use of translucent sunshades or 
awnings. 

16. Tempering the light. The light due to the sunshine on 
such shades and awnings will be as bright as ordinary skylight 
if the shade is well chosen, and the ribbed glass will be still 
brighter. If the windows are large, the illumination is likely 
to be too great near the windows as previously pointed out and 
it should be reduced. This should not be done, however, by 
pulling down an opaque shade over the top of the windows 
because the top portion of the window is the part that is par¬ 
ticularly needed to give light to the interior of the room. The 
better scheme is to employ an opaque shade which should be 
raised from the bottom of the window. This will reduce the 
illumination near the window without affecting it over the 
interior of the room to any marked degree. 

17. Bench locations. Fig. 2 shows how benches are com¬ 
monly located with respect to windows, so that the light received 
on the work may be most satisfactory. This, sets a certain 



ELEVATION 



Fig. 2. Diagram showing benches located 
with respect to the windows so as 
to receive the natural light advan¬ 
tageously. 


limitation upon the possible arrangement of the work over 
the floor space, depending on the way daylight is furnished to 
the floor area. This limitation can be eliminated almost com¬ 
pletely in the case of artificial light through a uniform dis¬ 
tribution of lamps overhead. This statement applies to those 

























TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 25 

cases where natural light is transmitted through side windows, 
and includes a feature specially noticeable in buildings of more 
than one story. In contrast, the work may be arranged almost 
independently of the natural light in buildings where the 
natural light is furnished by overhead windows or through 
the means of saw-tooth construction. 

18. Window glasses. Both translucent and clear glass are 
employed for factory and mill windows. There is a slight 
reduction in the transmitted light through ordinary translucent 
wire glass, but it is often required by insurance regulations 
for a deduction in the fire risk where a given building is located 
in close proximity to other buildings. Wire glass is also used 
quite generally with steel window frames, here being an added 
protection from the standpoint of fire risk. Wire glass may 
be obtained in clear form, but its expense in contrast to the 
translucent form is such as ordinarily to prohibit its use for 
industrial purposes. 

19. Wire glass. Wire glass, also known as ribbed glass, 
should be used and is advocated for practically all factory and 
mill windows where prisms are not required. Wires of rather 
open mesh cause so little reduction in light as to warrant no 
mention of this feature. Special care should be taken to get 
such glass as is smooth both on the flat side and on the ribbed 
side to facilitate cleaning. Wire or ribbed glass gives better 
diffusion than plain glass. 

20. Prism glass. Where the sky outside of the windows is 
obstructed by buildings, prism glass is recommended if the room 
is deep. Different kinds of prisms can not be used to advan¬ 
tage interchangeably. The amount of prism glass required 
in any case depends much upon the surroundings and to obtain 
excellent results, of which such glass is capable, it must be 
used intelligently. 

21. Skylights. Skylights are sometimes installed in long 
narrow continuous strips in a sloping roof. The ribs of the 
ribbed glass are generally so arranged that it is convenient 
to make them at right angles to the length of the strips. The 
result is that the sunshine is diffused by the ribs over a narrow 
area parallel to the strip of skylight, thus lighting one part 
of the room much more brilliantly than the remainder. If the 
ribs are installed'to run parallel to the strips, they will give 
a much more general distribution of the sunlight. In the 


26 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


foregoing, the word strip refers to the long belt of skylight and 
not to the individual sheet of glass. Ribbed glass in vertical 
windows should generally be placed with the ribs horizontal. 
They thus roughly fulfill some of the functions of prisms. 

22. Dirt accumulations. While translucent wire or ribbed 
glass reduces the amount of light transmitted through the 
windows, the roughness of the outside surface of such glass 
often causes accumulations of dust and dirt, which are more 
to blame for the reduction of transmitted light in some cases 
than the translucent nature of the glass itself. Remedies of 
this difficulty are to secure smooth glass and to resort to 
frequent cleaning. 

23. Wire glass as a safeguard. Wire glass for skylights is, 
of course, a practical necessity as a safeguard against accidents 
due to accidental breakage of the glass or due to objects falling 
on top of the glass. 

24. Sunshine not desirable. In all the work of providing 
natural light, it should be kept in mind that direct sunshine 
in itself, from the illumination standpoint, but irrespective of 
sanitary conditions, is not wanted. The idea that sunshine is 
the important item is a common but an erroneous impression. 
For example, in saw-tooth construction, the windows do not 
face the south to get all the sunshine possible, but they face 
the north to exclude the sunshine. Ordinarily windows, on 
the other hand, face all directions because not enough light 
can be distributed to interiors from north windows alone. 
Windows on the other than north fronts admit sunshine to be 
sure, and this makes sun shades and awnings necessary to 
exclude the excessive brightness. 

VALUE OF ADEQUATE ILLUMINATION. 

25. Factory and mill owners are concerned in the matter 
of securing the largest output for a given manufacturing 
expense. An improved machine tool capable of increasing 
the product for given labor costs is most attractive, provided 
its first cost is within returnable limits out of the larger profits. 
Improved small tools, better methods of handling material, 
adequate crane service, fire protection, good shop floors, 
accurate and efficient timekeeping methods, and similar items, 
vitally concern the shop manager; money is expended to realize 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 27 

excellence in these features because they afford increased 
economies and protection, thus resulting in a higher efficiency 
of the plant. 

26. Energy consumption a minor item. Many arguments 
leading to the sale of gas and electric lamps for use in factory 
and mill buildings are based on reducing the lamp operation 
cost of substituting a new for an older system. Arguments 
of this kind are of value, however, only when such a reduction 
in operation cost can be effected without sacrifice in the ade¬ 
quacy of the illumination. It would be a poor policy, in the 
extreme, to argue a saving in energy consumption by the sub¬ 
stitution of one type of lamp for another on a basis of equal 
candlepower in both old and new systems. 

27. Effect of good light on production. Arguments of a 
convincing nature, which insure to the factory or mill man¬ 
ager an increased output through improved illumination 
service, are of importance and even greater at times than 
reductions in the cost of illumination for the same quantities 
of light. In view of the fact that resulting advantages of 
superior illumination on increased output are apt greatly to 
exceed economies in operation cost as regards the lighting 
system, it is a distinct advantage to direct and hold the atten¬ 
tion on the former rather than on the latter. This statement 
will be more apparent when interpreted into definite items 
as follows: 

28. Advantages of good light. While the necessity of good 
natural and artificial light is so evident that a list of its effects 
may seem commonplace, these same effects are of such great 
importance in their relation to factory and mill management, 
that they are well worth careful attention. The effects of good 
light, both natural and artificial, and of bright and cheerful 
interior surroundings, include the following items: 

1. Reduction of accidents. 

2. Greater accuracy in workmanship. 

3. Increased production for the same labor cost. 

4. Less eyestrain. 

5. Promote better working and living conditions. 

6. Greater contentment of the workmen. 

7. More order and neatness in the plant. 

8. Supervision of the men made easier. 

In this list it will be noted that items 4, 5, 6, 7 and 8 all have 
a bearing on accident prevention. 


28 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


29. Interpreting the advantages of good light. While the 
major consideration in the eyes of the factory or mill owner 
is undoubtedly and quite naturally the money value of good 
light in the larger return of both quantity and quality of work 
which may result from the installation of a superior as com¬ 
pared with an inferior lighting system, it should be noted that 
it is very difficult to interpret into dollars and cents the value 
of good light made possible by such returns. This difficulty 
is due to the necessity of keeping all conditions in a factory or 
mill section absolutely constant while varying the amount of 
illumination from poor to good conditions, in an effort to 
determine the output and its dependency on the light facilities. 
As accurate data becomes available, giving the increases in 
production for certain specific improvements in artificial light¬ 
ing, it will doubtless prove helpful to a proper interpretation 
of adequate light and its worth to any plant. 

The eight foregoing points are emphasized as forming the 
most important features in the problem of good lighting. 
Although difficult to interpret into money values, and some¬ 
what intangible, they are indisputable arguments in favor of 
the best available illumination from the standpoint of the 
factory or mill owner. 

30. Practical example. Continuing from the manufacturer’s 
point of view, it may be said that certain assumptions as to 
energy cost, cleaning, interest and depreciation, show that the 
annual operation and maintenance cost for the illumination 
of a typical shop bay of 640 square feet area, may be taken 
at $50.00. If five workmen are employed in such a bay at an 
average wage of say 25 cents per hour, the gross wages of the 
men in such a bay, plus the cost of superintendence and indi¬ 
rect shop expense, may equal from $5,000 to $7,000 per annum. 
In a case of this kind, therefore, the lighting will cost from 
tV to 1 per cent of the wages, or the equivalent of less than 
4 to 6 minutes per day. We may roughly say that a poor 
lighting system will cost at least one-half this amount (some¬ 
times even more through the use of inefficient lamps and a poor 
arrangement of lamps), or the equivalent of say 2 to 3 minutes 
per day. Nearly all factories and mills have at least some 
artificial light, hence, in general, if good light enables a man 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


29 


to do better or more work to the extent of from 2 to 3 minutes 
per day, the installation of good lighting will easily pay for 
the difference between good and bad light, through the time 
saved for the workmen. 

31. Actual losses. Superintendents have stated in actual 
instances, that due to poor light their workmen have lost much 
time, sometimes as much as from one to two hours per day on 
certain days. If good light will add an average of say one- 
half an hour per day to the output, these 30 additional effective 
minutes represent an increase in output of 5 per cent, brought 
about through an expenditure equal to J of 1 per cent of the 
wages for improved lighting, or a saving equal to ten times the 
expense. 

OLD AND NEW LAMPS. 

32. The inadequate means available for illumination by 
artificial methods in the past have contributed to the slowness 
of an appreciation of the features of artificial light which 
influence the working efficiency, of the eye. Open flame gas 
burners, carbon incandescent and arc lamps, practically the 
only illuminants available ten years or so ago, play but a 
small part in the present approved methods of factory and 
mill lighting. 

33. New lamps. The large variety of comparatively new 
lamps available for factory and mill lighting includes the 
mercury vapor, metallized filament, tungsten, gas-filled tung¬ 
sten, metallic flame or magnetite arc, the flame carbon arc, 
the quartz mercury vapor, and various types of gas arc lamps. 
Remarkable improvements have thus been made in both the 
electric and gas lighting fields, the same general rules of 
applying the lamps covering both of these fields. Possibilities 
in factory and mill lighting are now attainable which, before 
the introduction of these new lamps, were either unthought 
of or impossible. Consideration of the eye as a delicate organ, 
together with the new ideas of the items which affect its comfort 
and efficiency, have resulted in establishing certain principles 
in illumination work, and have directed attention naturally 
and in a growing manner to the proper use and application of 
these new lamps. 


30 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


EFFECTS ON FACTORY AND MILL LIGHTING PRODUCED 
BY MODERN LAMPS. 

34. With the introduction of these new gas and electric 
lamps, broader possibilities have been presented in factory 
and mill lighting. The use of units of sizes adapted to the 
purposes, allows results which it has been hitherto impossible 
to obtain satisfactorily, either by the arc lamp, carbon filament 
or open flame gas burner, formerly available. 

35. New possibilities. It is evident that the introduction of 
the many new lamps has made possible what may be termed 
a new era in industrial illumination, a distinctive feature of 
which is the scientific installation of the lighting units, suiting 
each to the location and class of work for which it is best 
adapted. Before the availability in recent years of medium 
sized gas and electric units the choice of the size of unit for 
a given location was often no choice at all. In many cases, due 
to small clearance between cranes and ceilings, or other con¬ 
ditions making it necessary to mount the lamps very high above 
the floor, but one size or type of unit was available, the carbon 
filament or open flame gas burner in the former, and the arc 
lamp in the latter case. 

36. Low ceilings. For low ceilings, up to 18 feet, the use 
either of carbon filament, open flame gas burner, or arc lamps 
resulted usually in anything but uniform light over the work¬ 
ing plane, and often produced merely a low general light 
which was practically useless for the individual machine. In 
such instances, individual lamps had to be placed over and close 
to the machines. With this arrangement, a relatively small 
area is lighted by each lamp and the metal shades usually 
employed serve only to accentuate the “spot lighting” effect. 
Such a form of illumination for factory and mill - work is 
unsatisfactory and inefficient, but, as stated, was in the past 
in many cases the only available scheme. The absence of 
lamps of the proper size is no longer an excuse for the exist¬ 
ence of such conditions in industrial plants. 

GENERAL REQUIREMENTS OF ARTIFICIAL LIGHTING. 

37. The following requirements for factory and mill lighting 
are made all the more important by the peculiar limitations and 
the wide variety of conditions to be found in factory and mill 
buildings and in factory and mill work: 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 31 

1. Sufficient illumination should usually be provided for 
each workman irrespective of his position on the floor 
space. 

2. The lamps should be installed and selected so as to 
avoid eyestrain to the workmen. 

3. The lamps should be operated from sources of supply 
which will insure reliable illumination results, particularly 
on account of the demoralizing effect by intermittent 
service, just when the light may be most needed. 

4. Adequate illumination should be provided from over¬ 
head lamps so that sharp shadows may be prevented as 
much as possible, and in such measure that individual 
lamps close to the work may be unnecessary except in 
special cases. 

5. The type and size of lamp should be adapted to the 
particular ceiling height and class of work in question. 

6. In addition to the illumination provided by overhead 
lamps, individual lamps should be placed close to the work 
if they are absolutely necessary in the eyes of a lighting 
expert, and in such cases the lamps should be provided 
with suitable opaque reflectors. 

These requirements may now be met by means of the new 
types of gas and electric lamps, one type of which can usually 
be found for practically each factory and mill location, espe¬ 
cially adapted to the general physical conditions of the location 
as typified by the clearance between cranes and ceiling and 
other similar items. 

OVERHEAD AND SPECIFIC METHODS OF ARTIFICIAL 
LIGHTING. 

38. Factory and mill lighting may be classified under two 
general divisions: First, distributed illumination furnished 
from lamps mounted overhead; and second, distributed illumi¬ 
nation furnished by individual lamps located close to the work. 
For practical purposes this classification is sufficient. In 
numerous cases a combination of these two methods becomes 
necessary. 

39. Mounting the lamps high. Where the lamps are high 
enough to be out of the line of ordinary vision, and are of a 
size and so spaced as to furnish illumination at any position 
on the floor where work may be carried on, the system is 
referred to as the overhead method of lighting. This method 
has many advantages. Its general adoption, which has been 


32 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


somewhat slow, has increased with the appearance of the many 
new types of lamps and with the growing appreciation of the 
value of good lighting. 

40. Where a small amount of general or overhead lighting 
is coupled with specific lighting from individual lamps, a large 
part of the floor space in many shops is in relative darkness, 
and much dependence must be placed on the hand lamps close 
to the work. The small number of overhead lamps generally 
used in such cases furnishes merely a small amount of addi¬ 
tional illumination over the floor space which is not sufficient 
to be of much value. However, where sufficient intensity is 
provided by general illumination, this is often a very effective 
means of lighting a large workroom. 

41. Low ceiling. Locations with low ceilings, until recently, 
have been lighted by the individual hand lamp method, because 
the old carbon filament lamps, being of low candlepower, could 
not well be used close to the ceiling, while the old type of arc 
lamp was often impracticable, due to its large physical size, 
*as well as its relatively high candlepower. This statement is 
subject to some modification, because low candlepower units 
have sometimes been used in clusters for low ceilings as a com¬ 
promise between a single small or a single large unit, this 
scheme being, however, usually insufficient and unsatisfactory 
in comparison with modern methods of lighting. In a partic¬ 
ular manner, therefore, suitable illumination has been difficult 
with low ceilings. 

42. New types of gas and electric lamps have a range of 
candlepower from very low to very high values, and the over¬ 
head system with the elimination of individual lamps is thus 
possible; in other words, a size of gas or electric lamp may now 
be selected from a large available list of sizes for nearly every 
factory or mill condition. 

VARIOUS LOCATIONS ILLUSTRATED.* 

43. Figs. 3 to 12 inclusive are given to indicate how the' 
problem of adequate illumination has been solved in a number 
of actual instances, and the following notes apply to some of 
the considerations involved. 

*Figs. 3 to 12 inclusive are, in general, arranged in the order of their 
mounting heights. The low mounting heights are shown in the earlier 
illustrations and the higher mountings in the later views. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 33 

There are two main items to consider in deciding for or 
against high candlepower lamps for the factory or mill. First, 
how high are the lamps to be mounted; and second, will the 
light at any given point on the machines or other operations 
be satisfactory if it comes from a few lamps or should it come 
from many sources'? If the ceiling or overhead construction 
is under 16 feet, lamps of high candlepower can hardly be 
used in sufficient numbers to produce uniform illumination 
over the floor space. If they are to be mounted at a height 
between 16 and 25 feet, it is largely a question of whether 
light from a relatively few lamps will produce satisfactory 
results. For mounting heights over 25 feet, lamps of high 
candlepower possess some advantages, chief of which is their 
large volume of light for given energy consumed, always pro¬ 
vided the light is effectively directed towards the floor. 

44. Three groupings. These three groupings by mounting 
heights are conveniently shown in Figs. 15, 16, 17 and 18. In 
Fig. 15, a single shop bay with a ceiling height of 12 feet is 
shown as typical of the first grouping. The single high candle- 
power lamp furnishes approximately the same amount of light* 
to the machines as do the eight small lamps. Note, however, 
that the illumination from the large lamp is not nearly as 
uniform as that from the small lamps, although the spacing 
of both the small and the large lamps- as represented in this 
illustration is typical of many actual installations. Note also 
that the shadows cast by the large lamp at certain portions of 
the floor space must be so marked as to make the illumination 
it furnishes very inferior in this respect to the illumination 
from the smaller lamps, because of their larger number. 

Here, if the number of large lamps for the given floor area 
be increased in an endeavor to make the illumination more uni¬ 
form and to reduce the shadows, the expense as compared with 
that for smaller lamps, makes the large lamps a very unfavor¬ 
able proposition. These two features are the basis for stating 
that in general large lamps are not desirable for mounting 
under 16 feet, and an analysis of conditions, together with 
a careful and unbiased comparison with the illumination 
produced by smaller lamps, will nearly always bear out this 
conclusion. 

45. Second grouping. In Fig. 17, a 20-foot ceiling has been 
selected as typical of the second grouping, a single shop bay 


34 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

being shown. Here the work is assumed to be rough assembly, 
mostly on horizontal surfaces, and the single high candlepower 
lamp, besides giving more nearly uniform illumination, because 
the light is distributed more broadly due to the increased 
height, is correspondingly more satisfactory as to shadows 
produced by the large lamp in the preceding illustration 
(Fig. 15), on account of the improved direction in which much 
of the light reaches the work. In this case, the arrangement 
of both large and small lamps is typical of many existing 
installations. 

46. In Fig. 16, however, although the height is the same as 
in Fig. 17, the work is quite different, being conducted on the 
inside of large vertical tanks. It would obviously be impos¬ 
sible to perform this work by the light from the single large 
lamp as well as with that from the larger number of medium 
sized lamps, even if the actual amount of light from each was 
the same, on account of the poor direction of the light at cer¬ 
tain positions of the work from a single unit in such a case. 
The medium sized lamps furnish approximately the same 
‘quantity of light and yet no matter where the tanks may be 
placed, they will receive considerable light from the medium 
sized lamps directly over or nearly over them, at least far more 
than is apt to reach them from a single unit in every other 
bay (the assumed arrangement of the large lamps). 

47. For this second grouping of mounting heights, then, the 
large lamps may or may not be adapted, depending on whether 
the reduction of shadows is of much importance, as is the case 
in Fig. 16. The large lamp is, however, more likely to be 
satisfactory here than in the first case (Fig. 15), because of 
the better distribution of the light due to the higher mounting, 
a fact made evident in Figs. 15 and 17 on account of the 
decreased number of small lamps and the increase in their 
size made possible in Fig. 17 as compared with Fig. 15, where 
the mounting is lower. By the same line of argument, it can 
be shown that for higher mountings, large lamps are still more 
likely to prove satisfactory. 

48. In Fig. 16, the number of large lamps might have been 
increased for the given floor area, but to have done so would 
mean that the cost for the energy and upkeep to maintain 
them would be excessive in comparison with the smaller types 
of lamps. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS 


35 



Fig. 3. Night view of a rather low factory section showing tungsten lamps 
of the 250-watt size mounted 12 feet above the floor. Note the 
original individual lamps over the machines. 



Fig. 4. Night view showing mercury-vapor lighting in low factory section. 

The lamps are about 12 feet above the work. Note the comparative 
absence of shadows. 






















36 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS 



Fig. 5. Day view of a gas lighting installation in a low factory section. 


This photograph shows merely the general arrangement of lamps and 
gives no idea of the illumination effect. 



Fig. 6. Night view of a planing mill showing an installation of 250-watt 
tungsten lamps with a 16-foot mounting. Note the excellent distribu¬ 
tion of the light and the comparative absence of shadows. This is an 
example of the overhead method of lighting. 



























TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


37 



Fig. 7. Night view of a boiler shop. 



Fig. 8. Day view showing arrangement of gas 
lamps in a medium high factory space. 
Note the pierced reflectors over the 
machine tools near the center of the 
picture. 
















38 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS 



Fig. 9. Night view of factory section with relatively high mounting of 
250-watt tungsten lamps. The lamps are 20 feet above the floor. 
Note the excellent distribution of the light and the shielding effect of 
the girders which serve to reduce the glare as one looks down the 
aisle. 



Fig. 10. Night view of arc lamp installation with 40-foot mounting at center 
of picture and 20-foot at sides. Excellent distribution. 


















TENTATIVE GENERAL LIGHTING SAFETY ORDERS 


39 



Fig. 11. Day view of relatively high section, showing a system of gas lighting. 



Fig. 12. High section showing a system of mercury-vapor lamps. Note the 
excellent distribution of light over the floor area. 
























40 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 



Fig. 13. Excessively bad lighting. Bare lamps produce a glare which is 
harmful and renders the illumination very ineffective. Compare 
with Fig. 14. 



Fig. 14. Example of good tungsten lighting with metal reflectors. Note the 
row of lamps near the ceiling for producing general illumination. 
This is known as combined general and localized illumination. Com¬ 
pare with Fig. 13. 






















TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


41 



PLAN 

Fig. 15. Diagram showing alternate schemes 
for lighting a low factory section. 
This contrasts the use of large and 
small lamps for a mounting height of 
12 feet. 



Fig. 16. Diagram contrasting the use of 
large and medium size lamps for 
mounting height of 20 feet. 



Fig. 17. Diagram of same factory space 
shown in Fig. 16, but with a 
different class of work. This 
view contrasts the use of large 
and medium sized lamps for a 
20-foot mounting. 



























































































42 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

49. Third grouping. In Fig. 18, the third grouping of 
mounting heights is shown with the lamps about 50 feet above 
the floor. In this illustration the distribution of the light 
from the large lamps will be far more satisfactory, both for 
flat and tall work than in the two preceding cases. It will be 
noted further that the increased height of the lamp causes the 
light to fall in such directions as to distribute it evenly over 



Fig. 18. Diagram showing the use of large lamps 
for a mounting height of 50 feet. 

the entire floor space taken care of by this one lamp in much 
better shape than for the lower mounting heights. (See also 
Figs. 19 to 23, inclusive.) 

LIGHTING CIRCUITS FOR ELECTRIC LAMPS AND SUPPLY 
MAINS FOR GAS LAMPS. 

50. The question of lighting circuits is mentioned here with 
particular reference to factory and mill conditions, where 
motor loads are apt to be large in comparison to the energy 


























TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


43 


consumption of electric lamps which are in service. In some 
eases, the proportion of motor load to lighting load is in the 
ratio of 10 to 1, in others 7 to 1, and so on, and the varying 
demands on the circuits by motors may greatly affect the lamps. 
Hence it is important to maintain strictly separate supply 
circuits for the lamps in order to avoid varying voltage which 
is apt to result if the motors are connected to the same circuits 
with the lamps. 



P L^N 


Fig. 19. This shows a very 
poor arrangement 
of artificial lighting 
by means of large 
lamps mounted too 
close to the floor. 
Compare this poor 
lighting scheme 
with the improved 
plan in Fig. 20. 



Fig. 20. This illustration is 
to be compared 
with Fig. 19. It 
indicates an im¬ 
proved scheme over 
that shown in 
Fig. 19 ; made pos¬ 
sible by the use of 
smaller lamps. 


51. Constant voltage. In addition to the superior illumina¬ 
tion resulting from lamps supplied from constant voltage 
mains, some types operate with longer life or very much better 
mechanically when supplied with constant voltage than other¬ 
wise. These features will therefore generally more than offset 
the somewhat greater cost of maintaining separate circuits for 
each class of service. In like manner and for similar reasons, 
it is advisable to place gas lamps on supply lines separate from 


those delivering gas for power purposes. 


CONTROL OF LAMPS AND ARRANGEMENT OF SWITCHES. 

52 The control of lamps in factory and mill lighting is 
important in all cases, but specially so where a large number 
of lamps is used in preference to a small number for a given 
















































44 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 



D LAN 
Fig. 21. 




These three illustrations show various ways in which a factory space of 16 ft. 
girder clearance can be handled, depending on the class of work performed. 
The first case, Fig. 21, is fairly satisfactory for storage spaces, and either 
the second or third cases, Figs. 22 or 23, can be employed for bench assembly 
or manufacturing. The third case, Fig. 23, is to be preferred where the 
class of work consists of the handling of small machinery parts. 







































































































TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 45 

floor area. For example, where an overhead system of tung¬ 
sten lamps of small size is used, a large number will, of course, 
be necessary for a given floor area, and in such cases the 
number of control circuits may at times seem excessive when 
planned out for sufficient flexibility of operation. Such cir¬ 
cuits, however, in rendering the system more flexible, will be 
more than paid for by the saving in energy and maintenance 
due to the turning out of lamps not needed in certain sections 
of the factory or mill, provided the number of hours per day 
during which the lamps are used on the average is relatively 
large, and the differences in daylight intensities over the floor 
area is also relatively large. 

53. Control parallel to windows. The lamps most distant 
from the windows will usually be required at times when the 
natural light near the windows is entirely adequate, thus 
making it an advantage to arrange the groups of lamps in 
circuits parallel to the windows. The advantages of this 
method are further apparent when it is considered that if the 
lamps are controlled in rows perpendicular to the windows, 
all lamps in a row will necessarily be on at one time, while 
a portion only may be required. 

54. Practical case. The foregoing statement may be devel¬ 
oped into a definite proposition. Thus, to install a single 
switch may involve say $5.00 as its first cost. If ten lamps are 
to be controlled from a single switch, these ten lamps must 
obviously either all be turned off at a time or all turned on 
at a time. An additional switch at a cost of $5.00 will permit 
either half of these ten lamps being turned off, if not required 
at certain times when the remaining five are needed. This 
extra switch may or may not be an economy. Consider, for 
example, the case where these five lamps are of the 60-watt 
tungsten type, and that they are turned off by the extra switch 
on an average of one-half an hour per day while the others are 
needed, or vice versa. In a year’s time, the energy saved at 
1 cent per kilowatt-hour, will amount to perhaps 50 cents. 
At this rate it will require ten years for the energy saved to 
pay for the first cost of the extra switch. This would not be 
considered a distinct economy. If, however, the energy cost 
be greater, and more nearly the average under actual con¬ 
ditions, or if the number of hours per day during which a 


46 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


portion only of the lamps will not be used, be greater, then 
these values will be correspondingly modified. 

55. Locating switches and controls. In locating switches 
or controls in factory and mill aisles, care should be exercised 
to arrange them systematically, that is, on columns situated 
on the same side of the aisle and on the same relative side of 
each column. This plan materially simplifies the finding of 
switches or. controls, by those responsible for turning on and 
off the lamps, and is particularly important where a given 
floor space is illuminated by a large number of small or medium 
sized lamps distributed uniformly over the ceiling area, a fea¬ 
ture which is usually accompanied by the use of a relatively 
large number of switches or controls. 

SYSTEMATIC PROCEDURE SHOULD BE FOLLOWED IN 
CHANGING A POOR LIGHTING SYSTEM OVER TO AN 
IMPROVED ARRANGEMENT. 

56. When undertaking the change from an old to a new 
lighting system, the various forms of illumination which are 
adapted to factory and mill spaces should be studied, and an 
investigation made of the various types of gas and electric 
lamps on the market which are available for the purpose. 

57. Time should be allowed for a study of the given locations 
to be lighted; for preparing the plans of procedure in the 
installation of the gas or electric lamps and auxiliaries; and 
for customary delays in the receipt of the necessary supplies 
and accessories to the work in hand. Altogether, therefore, 
work of this kind requires considerable time for its completion. 

58. Using the shop force. In large factories or mills, a 
wiring or gas-fitting force is sometimes a part of the. mainte¬ 
nance division. The work of the wiremen or fitters is likely 
to be heaviest in the winter, due to the dark days. Where 
this condition exists, there is all the more reason to apportion 
out new work so as to accomplish it during the months of least 
wiring and piping repair activity, and further, at that time 
of the year when employees will be comparatively unaffected 
by the disturbances usually associated with a change from an 
old to a new lighting system through possible irregularities 
in the illumination service while the wiremen or fitters are 
at work. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 47 

59. Distribution of expense. Another feature different 
from the foregoing viewpoint is in the distribution of the 
installation cost over a relatively long interval. If, for 
example, the system is desired for the approaching winter, the 
complete wiring or piping plans may be drawn up and blocked 
out into three, four or even more sections, thus spreading the 
expense over as many months. 

60. Yearly appropriation. In some shops a given appro¬ 
priation may be allotted each year for building equipment. 
From the standpoint of finance plans, it may thus be desirable 
to distribute outlays of this nature over the year, rather than 
to concentrate them at any one time. An important consid¬ 
eration in this method of installing lamps, however, is to 
prepare in as far as possible the complete plans in advance, 
at least as regards given factory or mill sections, so as to insure 
a uniform and symmetrical installation as a whole when the 
component parts are finished. 

REFLECTORS AND THEIR EFFECT ON EFFICIENCY. 

61. A reflector or shade is used in conjunction with a lamp 
for the purpose of reducing the glare otherwise caused by 
looking directly into the bare lamp, as well as for the purpose 
of redirecting the light most effectively to the work. 

62. Reflectors and shades, both metal and glass, are now 
obtainable for each size of incandescent electric and gas lamp. 
For a certain ratio between the spacing and the height of the 
lamps, a reflector can nearly always be selected which will 
furnish uniform illumination over the working surface. 

63. Function of reflector. Owing to the direction of the 
light from the lamp, nearly all types of lamps, in addition 
to the downward light, furnish some rays which go upwards 
and away in other directions from the objects to be illumi¬ 
nated, and are therefore relatively not useful. Furthermore, 
a bright source in the field of vision causes an involuntary 
contraction of the pupil of the eye, which is equivalent to a 
decrease in illumination in so far as the eye is concerned. 
Hence, while reflectors or shades may at first seem to reduce 
the amount of light in the upper part of the room, their use 
actually increases the amount of light in a downward useful 
direction, and improves the “■seeing,” due to the better con¬ 
ditions which surround the eyes. The economic function of 


48 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


the reflector as contrasted to this easier condition it affords 
the eyes, is to intercept the otherwise useless or comparatively 
useless rays which do not ordinarily reach the work, and to 
reflect them in a useful direction. In performing this func¬ 
tion, there is a choice through the design of the reflector, in 
the manner of distributing the light, so as to make the illu¬ 
mination on the floor space uniform with certain spacing 
distances and mounting heights as previously mentioned. 

64. Avoiding dark spots. With the use of lamps for which 
a. large variety of reflectors is available, the proper reflector 
should therefore be chosen so as to give the desired distribu¬ 
tion of light. In other cases, as in the use of the gas or electric 
arc lamps, where the globe or reflector is usually a fixed part 
of the lamp, care must be exercised to space the lamps at 
sufficiently close intervals to insure uniformity of the illumi¬ 
nation, that is, a freedom from the relatively dark spaces 
which exist between lamps when spaced too far apart. 

65. Light interiors. With a light ceiling, the reflection of 
that part of the light which passes through a glass reflector 
to the ceiling, and which is added to the light thrown down¬ 
ward from the under surface of the reflector, is a factor in 
building up the intensity of the illumination on the working 
surface. Great importance is therefore attached to light 
interior colors, especially on ceilings and the upper portions 
of walls, both in reinforcing the direct illumination, and in 
giving diffusion, which in turn adds to the amount of light 
received on the side of a piece of work. It should also be 
stated that the intensity of the light from bare overhead 
lamps when measured on the working surface may be increased 
by as much as 60 per cent through the use of efficient reflectors. 
This is due to the utilization of the horizontal rays of light 
as previously stated, which predominate in the bare lamp, 
whereas the most effective light in factory and mill work is 
apt to be that which is directed downward. 

66. Points to consider. Reflectors will not be classified here 
from the commercial standpoint, but the following items should 
be given consideration in the selection of the type of reflector 
for factory or mill use: 

1. Utilization efficiency. How much does the reflector 
contribute to the effective illumination on the work? 

2. The effect in reducing glare. 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 49 

3. Natural deterioration with age through accumula¬ 
tions of dust and dirt. 

4. Ease in handling and uniformity of manufacture. 

5. Physical strength and the absence of projections 
which may increase the breakage in case of glass reflectors. 

67. A study of the various reflectors on the market with the 
aid of these items as a basis will determine what reflectors are 
best adapted to given conditions. Eegarding the third item 
in the foregoing list, it may be stated that under comparative 
tests in service, the accumulations of dust and dirt on glass 
reflectors do not seem to be any greater than the coating of 
dirt which accumulates on the inside of a metal reflector in 
the same length of time. 

SIDE LIGHT IMPORTANT IN SOME FACTORY AND MILL 
OPERATIONS. 

68. It has been customary in many cases to measure the 
effectiveness of illumination in terms of the vertically down¬ 
ward component of the light. This method has ignored the 
value of side components in relation to vertical surfaces and 
openings in the side of the work. It is sometimes more 
necessary to light the side of the machine or the side of a 
piece of work than the horizontal surface. If, then, in design¬ 
ing a factory or mill lighting system, the prime object is the 
production of the greatest amount of downward illumination, 
it may happen that the side component is so small that the 
sides of machinery or of work are inadequately lighted. 

69. Two ways to secure side lights. Experience indicates 
that there are two general ways in which to secure adequate 
side lighting. One of these methods is to lower the lamps, 
and the other is to use broader distributing reflectors than are 
called for by the rules which consider uniformity of the down¬ 
ward illumination only. Side walls or other reflecting surfaces 
will modify the results. Thus, after the determination of a cer¬ 
tain type of reflector for producing uniform vertically down¬ 
ward illumination, it may be found that more side light is 
necessary, and this extra side component may, as stated, 
usually be secured by selecting a somewhat more distributing 
reflector. Broader distributing reflectors are apt to result in 
less downward illumination and will sometimes call for larger 
lamps than found necessary by preliminary calculations. 


50 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

70. Practical case. As an illustration, in a certain lighting 
system a vertically downward intensity of about 3 foot-candles 
was deemed sufficient for the work involved. Measurements 
and observations showed that the side light was insufficient. 
In this particular installation it was found necessary to pro¬ 
duce a vertically downward intensity of about 5 foot-candles 
on the average in order to secure an intensity of about 2 foot- 
candles on the side of the work, and also to use a somewhat 
broader distributingtreflector than at first chosen. Two foot- 
candles on the sides of the work were sufficient in this case 
where bench work and work in the vise on small machine parts 
were conducted. 

71 > Keeping the lamps high. It is recommended that the 
lamps be mounted near the ceiling in all reasonable cases 
where side light is necessary, and that the side light be 
increased, not by lowering the lamps, but through the medium 
of broader distributing reflectors and larger lamps ; if required. 
This attitude is taken on account of the glare '“Which results 
when lamps are mounted too close to the work, a feature most 
noticeable in the absence of a reflector or where glass reflectors 
are used. 

72. Maintenance. Provision should be made for systematic 
upkeep of natural and artificial lighting. 

73. Windows. Factory and mill windows become covered 
in time with dirt, and produce greatly decreased values of 
natural light in. consequence. These losses may easily be great 
enough to affect the workmen seriously, and to necessitate the 
use of artificial light at times when otherwise it would not be 
required. Dark surroundings also increase the likelihood of 
accidents. Regular window cleaning should therefore be a 
part of the routine of every factory and millvbuilding or group 
of buildings. 

74. Lamps. Carbon filament, mercury-vapor, gas mantle 
and tungsten lamps burn out or break, globes and reflectors 
become soiled, and the various other items of deterioration 
take place so gradually that in many cases they are given no 
special concern in the practical economy of the shop. More¬ 
over, it is hardly necessary to mention the fact that often 
lighting systems are allowed to deteriorate to an extreme point 
and nothing is done unless complaints come in from employees 
after the lighting facilities here and there throughout the shop 


51 




TENTATIVE GENERAL LIGHTING SAFETY tfRO'feRS. 



m 





have become so poor that work has to be discontinued tempo¬ 
rarily. The losses of time from such circumstances, when 
added up throughout a year, are more than likely to exceed 
the expense of systematic attention to such maintenance items 
in advance. ** 

75. Overhead system. Furthermore, with modern methods 
where the lamps are usually mounted overhead rather than 
close to each machine, the importance -<5f relieving the workmen 
from any care of the lamps, and placing it in the hands of a 
maintenance department is even greater than has been- the 
ease in the past, particularly in large plants. 

76. Reflector cleaning. The serious loss of light when globes 
and reflectors are allowed to go for - long periods without 
cleaning is shown in Fig. 25. This set of curves resulted from 
a test on a glass reflector used with a tungsten lamp. The 1 one 
curve shows the value of the light given by-the lamp at dif¬ 
ferent angles when the lamp and reflector are clean, while the 
smaller ctirwe shows the enormous reduction of light after the, 
lamp and reflector have been in service for about four months 
without being cleaned. 



Fig.' 25. Curves showing serious 
losses of light from a 
tungsten lamp and its 
reflector, due to accumu¬ 
lations of dirt. This is 
a condition applicable 
to all types of lamps, as 
other illuminants suffer 
corresponding losses 
from dirt accumulations. 


77. In this particular case, which is a typical one, the loss 
pf light at the end of the four-month interval amounted to 
about 50 per cent. The cost of electrical energy in this shop 
was such that the loss, of light during the fourth month 







52 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 



Fig. 26. Very poor lighting in a worsted goods factory. The wiring is badly 
arranged, the contrasts between light and dark portions of the room 
are excessive, and in some cases the wrong size of lamp is used in 
a given reflector. The system is unsightly and represents bad 
practice. Compare with Fig. 27. 



Fig. 27. Worsted mill with localized general illumination. This is an example 
of excellent illumination with tungsten and metal reflectors. Note 
the reflection from the goods to the ceiling. Compare with Fig. 26. 


















TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


53 



Fig. 28. Very poor arrangement of arc lamps. The lamps are mounted to 
one side of aisle over line shafting. Very little light reaches the 
machinery to the right. Compare with Fig. 29. 



Fig. 29. Well planned system of arc lighting. The lamps are high and above 
the ordinary line of vision. Compare with Fig. 28. 






















54 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


amounted to about 12 cents, while the total cost of taking 
down, washing and replacing this reflector amounted to 
about 3 cents. The economy of a fairly frequent attention to 
cleaning of such reflectors is at once apparent, even if the 
improved condition of the light in itself be ignored. 

78. The example just given will serve to illustrate the class 
of upkeep problems which are involved in shop lighting. The 
most forcible emphasis is applicable to the idea that system 
may properly be called a first step towards success in this line 
of maintenance work. 

79. A method of inspection and maintenance. In one large 
factory a regularly developed method of inspection and 
renewals is employed. As an example, the method as applied 
to several thousand tungsten lamps which are in service in 
the various buildings will be described. All the lamps are 
inspected once per day, except Saturday and Sunday. A 
regular route is followed by the inspector, and all burned out 
lamps, broken switches, loose fuses, and similar items are noted. 
Careful observation is also made of reflectors which appear 
to need washing and any other points which might affect the 
efficiency of the system, after which a report is made up about 
noon and promptly sent to the maintenance department to 
permit all renewals and repairs to be made before night. In 
this manner the lamps are well maintained from day to day. 

80. Marking columns. To facilitate this renewal work, it 
has been found advantageous to mark all columns through this 
shop. The inspector is thus enabled to indicate clearly the 
location of each burned out lamp and the renewal man to 
locate it without delay. It is helpful now and then in like 
manner to have the inspector note the unnecessary lamps 
found burning when artificial light is not required. If lamps 
are found burning at such times, a note sent to the head of 
the department calling attention to the matter, is usually 
sufficient to remedy the difficulty. 

81. Noting soiled reflectors. As a check on a regular 
cleaning schedule the inspector should note all reflectors in 
need of cleaning. The frequency of each cleaning will depend 
on the rate of deterioration due to the settlement of dirt on 
the surface of the glass or metal and also on the surface of 
lamps, and the fact should be kept in mind that the amount 
of dirt on a reflector is nearly always deceptive, that is, 


TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 


55 


reflectors which have suffered a large deterioration in efficiency 
due to dirt often appear fairly clean, and for this reason it is 
best to increase the frequency of cleaning somewhat over that 
which seems sufficient from observation, particularly in view 
of the fact that tests indicate large reductions of light from 
apparently small accumulations of dust and dirt. 

82. A method of washing. In the factory just referred to, 
all reflectors are removed to a central washing point. Where 
the number of reflectors to be hauled is large, a truck is used. 
Often, however, where only a small number of reflectors is to 
be transported, small hand racks, devised for the purpose, are 
employed. When an installation is in need of washing, the 
scheme is to haul sufficient clean reflectors to the location in 
question. The soiled reflectors are then taken down and clean 
ones immediately put into place, after which the soiled reflec¬ 
tors are removed to the central washing point, washed and 
put into stock for the next location. 

EXPERT ASSISTANCE SUGGESTED. 

83. The advantages of securing expert assistance in dealing 
with illumination are strongly emphasized. The points which 
come up for solution are complex and require, in many cases., 
the judgment of one who has had wide experience in the 
lighting field. 

OTHER FEATURES OF EYE PROTECTION. 

84. Care is urged on the part of those responsible for the 
health and welfare of employees to see that adequate eye pro¬ 
tection is afforded in all operations which are apt to cause 
injury to eyesight if such protection is neglected. As typical 
of such other causes of danger to eyesight, arc welding may 
be mentioned, where the operator, according to accepted prac¬ 
tice, must wear a helmet in general. Protective glasses for this 
purpose should not be judged as to their protective properties 
by mere visual inspection. They should, therefore, be analyzed 
for their spectral transmission of invisible radiation. Pro¬ 
tective measures should also be taken to prevent onlookers 
from being unduly exposed to such eye dangers, by enclosing 
the welding operations with suitable partitions. These gen¬ 
eral remarks apply with equal force from the standpoint of 
those handling the operations to such other cases as the testing 
of arc lamps, inspection of hot metal and similar cases. 


0 033 

56 TENTATIVE GENERAL LIGHTING SAFETY ORDERS. 

GOOD AND BAD LIGHTING COMPARED. 

85. In order to give an idea of good and bad lighting, 
Figs. 13, 14, 26, 27, 28 and 29 are shown. These illustrations 
indicate the use of various types of lamps and a reference to 
the captions under the illustrations will bring out the weak 
points of the poorly lighted spaces, as well as the points of 
excellence in those cases which are designed in conformity 
with good illumination practice. 

METHOD OF MEASURING SURFACE BRIGHTNESS. 

86. The candlepower of the brightest square inch of light 
source may be measured by means of a portable photometer. 
An opaque board with a square or circular hole one square 
inch in area is placed against the surface of the light source in 
such a position that the brightest spot emits light through the 
hole in the board. The board must be of such size as to pre¬ 
vent any other light from the source to strike the photometer. 
The photometer is placed at some convenient distance from the 
light source unit and read, care being taken to exclude all light 
from the photometer except that coming through the hole. 
If the photometer is read at a distance of one foot from the 
light source, the foot-candles observed will also be the candle- 
power; if the photometer is two feet distant from the light 
source, the foot-candles observed must be multiplied by four 
to obtain the candlepower; if three feet, they must be multi¬ 
plied by nine, etc., the observed foot-candles in all cases being 
multiplied by the square of the distance between the light 
source and the photometer, when the readings were taken to 
obtain the candlepower of the source. 


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44109 2-19 3M 


